Combustion apparatus and hot water apparatus

ABSTRACT

A combustion apparatus includes a chamber having an internal space, a fan having a first emission port which communicates with the internal space of the chamber in a first direction, and an ignition plug having a portion overlapping a region extending from the first emission port in the first direction in plan view.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a combustion apparatus and a hot water apparatus.

Description of the Background Art

A conventionally known combustion apparatus is disclosed in, for example, Japanese Patent Laying-Open No. 2018-112321.

Japanese Patent Laying-Open No. 2018-112321 discloses a combustion apparatus of premix burner type. In this combustion apparatus, an attachment surface of a chamber accommodated in a housing provided with an opening at its front and an attachment surface of a fan are disposed to be inclined toward the opening with respect to a back plate portion of the housing. In the combustion apparatus, an emission port of the fan and an intake port of the chamber are also disposed to be inclined similarly to the attachment surfaces.

SUMMARY OF THE INVENTION

In a common combustion apparatus of premix burner type, mixed gas of fuel gas and air mixed in the fan is supplied to the chamber.

However, a great amount of air is present in the chamber upon execution of the ignition sequence, that is, upon start of a supply of mixed gas to the chamber. For this reason, a period of time, which is required until the atmosphere around the ignition plug is replaced with mixed gas having an air-to-fuel ratio, which allows ignition, from the execution of the ignition sequence depends on the length of a flow path of mixed gas which extends from the fan to the ignition plug and also depends on the velocity distribution of the mixed gas.

Commonly, the ignition plug for igniting mixed gas is disposed on the front surface of a heat exchanger facing the opening of the housing for easy assembly and maintenance of the ignition plug.

When the combustion apparatus described in Japanese Patent Laying-Open No. 2018-112321 includes the ignition plug described above, thus, the length of the flow path of mixed gas which extends from the fan to the ignition plug is relatively long. In this case, a period of time from the execution of the ignition sequence to the replacement of the atmosphere around the ignition plug with mixed gas having an air-to-fuel ratio which allows ignition, that is, an ignition-requiring time required for ignition is relatively long.

An object of the present invention is to provide a combustion apparatus and a hot water apparatus that need a short ignition-requiring time compared with the combustion apparatus described in Japanese Patent Laying-Open No. 2018-112321.

A combustion apparatus of the present invention includes a chamber having an internal space, a fan having a first emission port which communicates with the internal space of the chamber in a first direction, and an ignition plug having a portion overlapping a region extending from the first emission port in the first direction in plan view.

This allows the mixed gas which has been blown out of the first emission port and flowed into the internal space of the chamber to reach the ignition plug without changing the direction of circulation in plan view. In the combustion apparatus, accordingly, the length of the flow path of the mixed gas which extends from the fan to the ignition plug is set to be short, resulting in a short ignition-requiring time compared with the combustion apparatus described in Japanese Patent Laying-Open No. 2018-112321.

In the combustion apparatus, the chamber has a second emission port which is open in a second direction different from the first direction. The first emission port and the ignition plug are disposed on an identical side with respect to a first center line passing through a center of the second emission port and running in the first direction as viewed from the second direction.

In such a combustion apparatus, also when the chamber and the fan are accommodated in the housing which opens in one direction, the first emission port and the ignition plug can be disposed to face one opening. In the combustion apparatus, accordingly, the first emission port and the ignition plug accommodated in the housing are easily accessible from the single opening. In the combustion apparatus, thus, assembly and maintenance can be enabled merely by an operation performed on the housing from one direction.

In the combustion apparatus, the first emission port and the ignition plug are disposed to sandwich a second center line therebetween, which passes through the center and is orthogonal to the first center line as viewed from the second direction. In the combustion apparatus, the mixed gas blown off in the first direction can flow along the wall of the chamber to reach the ignition plug efficiently.

In the combustion apparatus, the chamber includes a wall disposed to overlap the second emission port as viewed from the second direction. The wall is inclined to be away from the first emission port as closer to the second emission port.

The upper wall of such a chamber changes the direction of circulation of the mixed gas blown out of the first emission port from the first direction to the second direction. This allows the mixed gas blown off in the first direction to flow along the upper wall of the chamber to reach the ignition plug efficiently.

A hot water apparatus of the present invention includes the combustion apparatus described above, and a housing having an opening at its front. The combustion apparatus is accommodated in the housing such that the ignition plug faces the opening. Consequently, a hot water apparatus can be provided that includes a combustion apparatus having a short ignition-requiring time compared with the combustion apparatus described in Japanese Patent Laying-Open No. 2018-112321.

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically shows a configuration of a hot water apparatus in an embodiment of the present invention.

FIG. 2 is a perspective view showing an example configuration of part of a combustion apparatus shown in FIG. 1.

FIG. 3 is a top view showing a configuration of part of the combustion apparatus shown in FIG. 2.

FIG. 4 is a transparent view showing configurations of a chamber and an ignition plug of the combustion apparatus shown in FIG. 3.

FIG. 5 is a sectional view as seen from an arrow V-V in FIG. 4.

FIG. 6 is a sectional view as seen from an arrow VI-VI in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will be described below with reference to the drawings. In the present embodiment, a first direction refers to a horizontal direction, and a second direction refers to an up-down direction. In the following description, “forward” refers to a direction perpendicular to the first direction and the second direction. In the following description, “in plan view” refers to a point of view as seen from the second direction.

First, a configuration of a hot water apparatus in one embodiment of the present invention will be described with reference to FIG. 1.

As shown in FIG. 1, a hot water apparatus 100 of the present embodiment mainly includes a sensible heat recovery heat exchanger (primary heat exchanger) 10, a latent heat recovery heat exchanger (secondary heat exchanger) 20, a burner 30, a chamber 31, a fan (fan assembly) 32, a duct 33, a venturi 34, an orifice 35, a gas valve 36, a pipe 40, a bypass pipe 41, and a housing 50. All the above components except for housing 50 are disposed inside housing 50.

Gas valve 36, orifice 35, and venturi 34 are connected to a pipe in the stated order. Fuel gas can be supplied to this pipe from the outside of housing 50. The fuel gas supplied to this pipe flows through gas valve 36 and orifice 35 into venturi 34.

Gas valve 36 serves to switch supply and stop of the fuel gas and set the gas pressure at an inlet of venturi 34 to be equal to an air pressure. Venturi 34 serves to increase the velocity of flow of air to increase a negative pressure of a fuel gas introducing portion, thereby facilitating an inflow of the fuel gas. Venturi 34 is configured to take in air from the outside of housing 50. Venturi 34 is configured to mix the air taken in from the outside of housing 50 and the fuel gas supplied through the pipe.

Venturi 34 is connected to fan 32 through a pipe. Through this pipe, the mixed gas mixed in venturi 34 is fed to fan 32. Fan 32 serves to supply the mixed gas to burner 30 and facilitate mixing of the fuel gas and the air. Fan 32 mainly includes a fan case, an impeller disposed in the fan case, and a driving source (e.g., motor) for rotating the impeller.

Fan 32 is connected to chamber 31, and chamber 31 is connected to burner 30. The mixed gas supplied from fan 32 is fed to burner 30 through chamber 31.

Burner 30 serves to burn mixed gas to generate combustion gas serving as gas for heating. Burner 30 is a device of inverse combustion type which supplies combustion gas downward. The mixed gas issued from burner 30 is ignited by an ignition plug 14 to turn into combustion gas. Ignition plug 14 is provided in, for example, sensible heat recovery heat exchanger 10.

Burner 30, sensible heat recovery heat exchanger 10, and latent heat recovery heat exchanger 20 are connected to allow combustion gas to flow through sensible heat recovery heat exchanger 10 and latent heat recovery heat exchanger 20 in order. Specifically, sensible heat recovery heat exchanger 10 is attached below burner 30, and latent heat recovery heat exchanger 20 is attached below sensible heat recovery heat exchanger 10.

Latent heat recovery heat exchanger 20 is connected with duct 33, and duct 33 runs to the outside of housing 50. Consequently, the combustion gas that has flowed through latent heat recovery heat exchanger 20 is discharged to the outside of housing 50 through duct 33.

Each of sensible heat recovery heat exchanger 10 and latent heat recovery heat exchanger 20 serves to heat hot water through heat exchange between the combustion gas supplied from burner 30 and hot water.

Sensible heat recovery heat exchanger 10 serves to recover a sensible heat of the combustion gas generated by burner 30. Sensible heat recovery heat exchanger 10 mainly includes a case 11 and a heat absorption pipe 13. Latent heat recovery heat exchanger 20 serves to recover a latent heat of the combustion gas. Latent heat recovery heat exchanger 20 may be, for example, a plate type heat exchanger.

For example, when the temperature of the hot water introduced to sensible heat recovery heat exchanger 10 is low, or when an amount of heating by burner 30 is small, water vapors of the combustion gas condense in sensible heat recovery heat exchanger 10, generating condensed water (drainage water). Drainage water is generated also in latent heat recovery heat exchanger 20. Such drainage water flows through part of duct 33 to be discharged to the outside of housing 50.

Heat absorption pipe 13 of sensible heat recovery heat exchanger 10 and a heat transfer portion of latent heat recovery heat exchanger 20 are connected to each other by pipe 40. A portion of pipe 40, which is on the water entry side with respect to latent heat recovery heat exchanger 20, and a portion of pipe 40, which is on the hot water exit side with respect to sensible heat recovery heat exchanger 10, are bypassed by bypass pipe 41.

Bypass pipe 41 is connected with a bypass servo 42. Bypass servo 42 is configured to control a flow rate of water flowing through bypass pipe 41.

The water supplied to hot water apparatus 100 turns into hot water through heat exchange with the combustion gas in sensible heat recovery heat exchanger 10 and latent heat recovery heat exchanger 20. This allows hot water apparatus 100 to supply hot water.

A configuration of a combustion apparatus 200 for use in hot water apparatus 100 described above will now be described with reference to FIGS. 2 to 6. FIGS. 4 to 6 are transparent views in which chamber 31 is seen through. Combustion apparatus 200 mainly includes chamber 31, fan 32, ignition plug 14, and housing 50.

As shown in FIGS. 2 to 6, fan 32 includes a fan case 32 a, a motor 32 b, an impeller (not shown), a first emission port 32 c (FIG. 4), and a first attachment portion 32 d. The impeller is rotatably disposed inside fan case 32 a. Motor 32 b is attached to the upper portion of fan case 32 a. Motor 32 b provides a driving force for rotation to the impeller in fan case 32 a. First emission port 32 c communicates with the internal space of chamber 31 and discharges mixed gas from fan 32 toward chamber 31.

As shown in FIGS. 2 to 6, first emission port 32 c is provided in fan case 32 a. First emission port 32 c is in communication with the internal space of fan case 32 a in which the impeller is disposed. First emission port 32 c is open in a first direction X. First emission port 32 c is disposed in, for example, the internal space of chamber 31. First emission port 32 c is inclined to form an angle of inclination of, for example, more than 0 degrees and less than 90 degrees to first direction X.

First attachment portion 32 d is disposed around first emission port 32 c in fan case 32 a. First attachment portion 32 d is a portion fixed to a second attachment portion 31 d of a chamber case 31 a. First attachment portion 32 d includes, for example, a facing portion 32 da, which is disposed to face (facing portion 31 da of) second attachment portion 31 d, and an engagement portion 32 db, which is connected to facing portion 32 da and provided to engage with (engagement portion 31 db of) second attachment portion 31 d.

Fan case 32 a includes an insertion portion 32, which is provided to, for example, project in first direction X with respect to first attachment portion 32 d and inserted into chamber 31. In this case, first emission port 32 c is configured as an opening end of insertion portion 32 e. Fan case 32 a may include no insertion portion 32 e. First emission port 32 c may be disposed to be coplanar with the surface of first attachment portion 32 d which contacts chamber case 31 a.

As shown in FIGS. 3 to 5, chamber 31 supplies the mixed gas supplied from fan 32 to a plurality of burner ports 30 a of burner 30. Chamber 31 includes chamber case 31 a, a connection port 31 b, a second emission port 31 c, second attachment portion 31 d, and a third attachment portion 31 e.

Chamber case 31 a has an internal space forming a flow path of the mixed gas supplied from fan 32 to burner 30. The internal space of chamber case 31 a is connected to the internal space of fan case 32 a. Connection port 31 b and second emission port 31 c are provided as openings of chamber case 31 a and are in communication with the internal space of chamber case 31 a.

Chamber case 31 a includes an upper wall 31 f Upper wall 31 f is disposed to overlap second emission port 31 c as viewed from second direction Z. Upper wall 31 f is inclined to be away from first emission port 32 c as closer to second emission port 31 c.

Connection port 31 b is open in the direction opposite to first direction X. Connection port 31 b is an opening connected with first emission port 32 c of fan 32. Second emission port 31 c is open in second direction Z. Second emission port 31 c is an opening for supplying mixed gas to burner 30. The opening of connection port 31 b has, for example, a circular shape. The opening of second emission port 31 c has, for example, a rectangular shape.

Second attachment portion 31 d is disposed around connection port 31 b in chamber case 31 a. Second attachment portion 31 d is a portion fixed to first attachment portion 32 d of fan case 32 a. Second attachment portion 31 d includes, for example, facing portion 31 da disposed to face facing portion 32 da of first attachment portion 32 d, and engagement portion 31 db connected to facing portion 31 da and provided to engage with engagement portion 32 db of first attachment portion 32 d. Third attachment portion 31 e is disposed around second emission port 31 c in chamber case 31 a. Third attachment portion 31 e is a portion connected to sensible heat recovery heat exchanger 10.

As shown in FIGS. 5 and 6, burner 30 has burner ports 30 a. Burner 30 burns the mixed gas which has flowed through burner ports 30 a to produce flames. Burner 30 is connected to second emission port 31 c of chamber 31. For example, burner 30 is disposed to overlap the entire second emission port 31 c of chamber 31 in plan view.

As described above, ignition plug 14 is provided in, for example, sensible heat recovery heat exchanger 10. As shown in FIG. 3, ignition plug 14 includes a pair of ignition plug electrodes. Ignition plug 14 produces ignition sparks across the pair of ignition plug electrodes to produce flames in the mixed gas issued from burner 30.

As shown in FIGS. 3 and 4, ignition plug 14 is attached to the wall surface of case 11. Ignition plug 14 is attached to case 11 while passing through case 11. Ignition plug 14 includes a core, which is made of conductive material, and an insulator, which is made of electrical insulating material and covers part of the core. The core of ignition plug 14 has a tip end 14T located inside case 11. The core of ignition plug 14 is bent, for example, at one location inside case 11. The core of ignition plug 14 includes a portion extending, for example, horizontally, a portion extending toward burner 30 with respect to the above-mentioned portion, and a bent portion connecting the above-mentioned two portions. The portion of the core of ignition plug 14 which extends horizontally is attached to case 11 with the insulator therebetween. The portion of the core of ignition plug 14 which extends toward burner 30 has tip end 14T. As shown in FIG. 4, ignition plug 14 has a portion overlapping second emission port 31 c as viewed from second direction Z. Ignition plug 14 further has a portion overlapping a region R1 extending from first emission port 32 c in first direction X as viewed from second direction Z. In the present embodiment, region R1 extending form first emission port 32 c in first direction X as viewed from second direction Z refers to region R1 located within the range of the width of first attachment portion 32 d as viewed from second direction Z. In ignition plug 14, at least part of the portion overlapping second emission port 31 c as viewed from second direction Z forms a portion overlapping region R1 as viewed from second direction Z. The portion of ignition plug 14 which overlaps region R as viewed from second direction Z has tip end 14T of at least one ignition plug electrode of the pair of ignition plug electrodes. Preferably, the tip ends of the pair of ignition plug electrodes are disposed to overlap region R1 as viewed from second direction Z, as shown in FIG. 4.

More preferably, ignition plug 14 has a portion overlapping region R2 located within the range of the width of first emission port 32 c as viewed from second direction Z, as shown in FIG. 4. Region R2 is a partial region of region R1. For example, tip end 14T of one plug electrode of ignition plug 14 is disposed in region R2 as viewed from second direction Z. The tip end of the other plug electrode of ignition plug 14 is disposed in region R1 as viewed from second direction Z, though it is located outside of region R2. Alternatively, the tip ends of the pair of ignition plug electrodes may be disposed to overlap region R2 as viewed from second direction Z.

As shown in FIG. 3, housing 50 has an opening 50 a. Opening 50 a is provided at the front of housing 50 and is open forward, that is, in a third direction Y orthogonal to first direction X and second direction Z. Opening 50 a is closed by a front lid member (not shown) after components are assembled and housed in housing 50.

Sensible heat recovery heat exchanger 10, latent heat recovery heat exchanger 20, burner 30, chamber 31, fan 32, venturi 34, and the like are disposed in housing 50.

As shown in FIG. 3, ignition plug 14 is disposed in a portion of case 11 which faces opening 50 a of housing 50.

As shown in FIG. 4, first emission port 32 c and ignition plug 14 are disposed on the same side with respect to a first center line O1 passing through a center O of second emission port 31 c of chamber 31 and running in first direction X, as viewed from second direction Z.

As shown in FIG. 4, first emission port 32 c and ignition plug 14 are disposed to sandwich a second center line O2 therebetween, which passes through center O and is orthogonal to first center line O1, as viewed from second direction Z. In other words, first emission port 32 c and ignition plug 14 are disposed individually in two regions, which are adjacent to each other in first direction X with second center line O2 therebetween, among four regions partitioned by first center line O1 and second center line O2 as viewed from second direction Z. First emission port 32 c and ignition plug 14 are not dipsoed in two regions, which form an opposite angle with respect to center O, among the four regions.

The functions and effects of the present embodiment will now be described.

Combustion apparatus 200 includes chamber 31 having an internal space, fan 32 having a first emission port which communicates with the internal space of chamber 31 in first direction X, and ignition plug 14 including a portion overlapping region R1 extending from first emission port 32 c in first direction X in plan view.

Thus, the mixed gas which has been issued from first emission port 32 c and flowed into the internal space of chamber 31 can reach ignition plug 14 without changing the direction of circulation in plan view. Combustion apparatus 200 thus has a short flow path of mixed gas which extends from fan 32 to ignition plug 14 and accordingly has a short ignition-requiring time compared with the combustion apparatus described in Japanese Patent Laying-Open No. 2018-112321.

A typical combustion apparatus of premix burner type includes no mechanism for switching the capability of the combustion surface and is provided to ignite at once on the entire combustion surface during ignition. Thus, if an ignition lag or the like occurs for any reason after the execution of the ignition sequence, fuel gas filling the combustion chamber ignites explosively. In contrast, combustion apparatus 200 has a relatively short ignition-requiring time, and accordingly, less experiences such an explosive ignition as described above even when it includes no mechanism for switching the capability of the combustion surface.

In combustion apparatus 200, chamber 31 has second emission port 31 c which is open in second direction Z different from first direction X. First emission port 32 c and ignition plug 14 are disposed on an identical side with respect to first center line O1 passing through center O of second emission port 31 c and running in first direction X in plan view.

In such combustion apparatus 200, also when chamber 31 and fan 32 are accommodated in housing 50 which is open in one direction, first emission port 32 c and ignition plug 14 can be disposed to face the one opening. In combustion apparatus 200, thus, first emission port 32 c and ignition plug 14 accommodated in housing 50 are easily accessible from the one opening. In combustion apparatus 200, thus, assembly and maintenance are enabled merely by an operation performed on housing 50 from one direction.

In combustion apparatus 200, first emission port 32 c and ignition plug 14 are disposed to sandwich second center line O2 therebetween, which passes through center O and is orthogonal to first center line O1 as viewed from second direction Z.

In combustion apparatus 200, the mixed gas blown off in first direction X flows along upper wall 31 f of chamber 31, thereby reaching ignition plug 14 efficiently.

In combustion apparatus 200, chamber 31 includes upper wall 31 f disposed to overlap second emission port 31 c as viewed from second direction Z. Upper wall 31 f is inclined to be away from first emission port 32 c as closer to second emission port 31 c.

Upper wall 31 f of chamber 31 changes the direction of circulation of the mixed gas blown out of first emission port 32 c from first direction X to second direction Z. This allows the mixed gas blown off in first direction X to flow along upper wall 31 f of chamber 31 to reach ignition plug 14 efficiently.

Hot water apparatus 100 of the present invention includes combustion apparatus 200 and housing 50 having opening 50 a at its front. Combustion apparatus 200 is accommodated in housing 50 such that ignition plug 14 faces opening 50 a. Hot water apparatus 100 including combustion apparatus 200 accordingly has more improved performance of immediately providing hot water at a predetermined temperature than the hot water apparatus including the combustion apparatus described in Japanese Patent Laying-Open No. 2018-112321.

Although the embodiment of the present invention has been described as above, it should be understood that the embodiment disclosed herein is illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the meaning and scope equivalent to the terms of the claims. 

What is claimed is:
 1. A combustion apparatus comprising: a chamber having an internal space; a fan having a first emission port which communicates with the internal space of the chamber in a first direction; and an ignition plug having a portion overlapping a region extending from the first emission port in the first direction in plan view.
 2. The combustion apparatus according to claim 1, wherein the chamber has a second emission port which is open in a second direction different from the first direction, and the first emission port and the ignition plug are disposed on an identical side with respect to a first center line passing through a center of the second emission port and running in the first direction as viewed from the second direction.
 3. The combustion apparatus according to claim 2, wherein the first emission port and the ignition plug are disposed to sandwich a second center line therebetween, the second center line passing through the center and orthogonal to the first center line as viewed from the second direction.
 4. The combustion apparatus according to claim 2, wherein the chamber includes a wall disposed to overlap the second emission port as viewed from the second direction, and the wall is inclined to be away from the first emission port as closer to the second emission port.
 5. A hot water apparatus comprising: a combustion apparatus according to claim 1; and a housing having an opening at its front, wherein the combustion apparatus is accommodated in the housing such that the ignition plug faces the opening.
 6. The combustion apparatus according to claim 3, wherein the chamber includes a wall disposed to overlap the second emission port as viewed from the second direction, and the wall is inclined to be away from the first emission port as closer to the second emission port.
 7. A hot water apparatus comprising: a combustion apparatus according to claim 2; and a housing having an opening at its front, wherein the combustion apparatus is accommodated in the housing such that the ignition plug faces the opening.
 8. A hot water apparatus comprising: a combustion apparatus according to claim 3; and a housing having an opening at its front, wherein the combustion apparatus is accommodated in the housing such that the ignition plug faces the opening.
 9. A hot water apparatus comprising: a combustion apparatus according to claim 4; and a housing having an opening at its front, wherein the combustion apparatus is accommodated in the housing such that the ignition plug faces the opening.
 10. A hot water apparatus comprising: a combustion apparatus according to claim 6; and a housing having an opening at its front, wherein the combustion apparatus is accommodated in the housing such that the ignition plug faces the opening. 